The Microsoft .NET framework provides two namespaces, System.Net and System.Net.Sockets for managed implementation of Internet protocols that applications can use to send or receive data over the Internet . SMTP protocol is using for sending email from C#. SMTP stands for Simple Mail Transfer Protocol . C# using System.Net.Mail namespace for sending email . We can instantiate SmtpClient class and assign the Host and Port . The default port using SMTP is 25 , but it may vary different Mail Servers .

The following C# source code shows how to send an email from a Gmail address using SMTP server. The Gmail SMTP server name is smtp.gmail.com and the port using send mail is 587 and also using NetworkCredential for password based authentication.